Wood deck connection system and method of installation

ABSTRACT

A wood deck connection system and a method for the installation of wooden deck panels using the system is disclosed. The reliable shear withdrawal connection system comprises a headed connector mechanically fastened to a steel, concrete or wooden girder, a wood-based deck panel having a receiver hole bored therein, and a grout agent deposited throughout the receiver hole. The deck connection system enables top-side installation of deck panels and provides improved shear strength, withdrawal resistance, reliability and fatigue behavior of the wooden deck system.

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 60/316,313 filed Aug. 30, 2001.

BACKGROUND OF THE INVENTION

[0002] The present invention generally relates to a system and method for installing wood-based deck panels. More particularly, the present invention relates to the installation of wood-based deck panels onto a girder system. One common girder system is a bridge girder.

[0003] Many bridges show early advanced deterioration due to mechanical wear and corrosion caused by atmospheric pollutants, road salt, vehicle emissions, acid rain and other pollutants. Over a period of years, the mechanical wear and corrosion degrade the support strength, durability, and earthquake resistance of the deck system, thus requiring either reconstruction or replacement of the bridge deck.

[0004] Currently, the typical installation of wooden or glued-laminated bridge deck panels may include a lagged or bolted deck clip connector that attaches the deck panel to the bridge girders. Such installation techniques present the significant disadvantage that workers need to work underneath the bridge structure in order to install the deck panels. Furthermore, the tools and equipment utilized in installing such lag bolts and connectors are heavy and unwieldy. As a result, installation is a difficult and labor intensive task, frequently including added costs associated with the erection of scaffolding or carriage work platforms. Bottom side installation also prolongs project completion and increases road closure duration.

[0005] Another disadvantage of the connection devices used in modern wood decked bridge construction design is that they typically act as a friction based connection detail and do not provide a reliable connection capacity since the connection capacity is based on the surface condition of the connecting elements and the clamping force exerted on these elements. Timber bridge construction designs, however, require connectors that exhibit predictable and reliable mechanical performance characteristics in shear loading and withdrawal loading conditions. Timber bridge deck connectors must resist vehicular imposed loads such as braking loads and uplift. The deck to girder connections are a vital link in the structural behavior of a timber bridge and its long-term structural serviceability.

[0006] Thus, there is a need for a rapid and cost effective installation system for wood-based deck panels which would allow for simplified installation from the top side of the deck panels. Providing such an installation system would reduce labor requirements and construction costs while supplying a reliable load transfer mechanism between the deck system and superstructure.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide a deck connection system and a method for installing a wood deck panel using the connection system, wherein the above deficiencies of the prior art are overcome and the problems of complicated installation and high cost are avoided.

[0008] The present invention achieves the above-mentioned object by providing, in a first aspect, a deck connection system comprising a wood-based deck panel containing a receiver hole that runs through the deck panel such that the hole begins on the upper surface of the deck panel and terminates on the bottom of the deck panel. The deck panel rests on a principal load carrying structure (also referred to as a “girder”) made from a concrete, steel, or wood-based material. A vertical headed connector, secured to the upper portion of the girder, projects upwardly into the receiver hole, wherein a cured grout agent deposited within the receiver hole provides a permanent mechanical connection between the headed connector and the assembled deck panel.

[0009] According to a second aspect of the invention, there is provided a method for installing a wood-based deck panel on a girder system comprising the steps of: securing a vertical headed connector to a girder system, mounting a deck panel having a receiver hole disposed therein onto an upper portion of the girder, depositing a grout agent into the receiver hole of the assembled deck system, and allowing the grout to cure so that a solid mechanical connection between the headed connector and the deck panel is formed.

[0010] Another advantage of the present invention is its high degree of reliability as measured in laboratory tests of a representative connection configuration, a glued-laminated (glulam) timber deck, steel girder, welded shear stud connection. This particular connection configuration possesses a low coefficient of variation of measured strength, less than 8.2 percent. Load-slip characteristics of the deck connector system after 15 million cycles of fatigue loading to 2,200 pounds show that the system retains more than 87 percent of its original connection strength. It is also 5 to 6 times stronger than traditional offset shoe connections. The normalized average stiffness (ratio of stiffness after 15 million load cycles to the stiffness after one load cycle) of parallel and perpendicular to grain specimens is 0.48 and 0.74, respectively. The glued-laminated timber deck-shear stud connection system is thus appropriate for bridges with a 100 year life cycle and an average daily truck traffic volume of 400 per day.

[0011] Yet another advantage of the present invention is that the deck connection system is acceptable for use at any wood grain angle. Static tests involving wood-based panels and steel girders show that the present deck connection system is superior in terms of strength and stiffness to the existing offset shoe connection that is frequently used for fastening timber decks to steel girders in new construction and bridge rehabilitation.

[0012] An additional advantage of the present invention is the significant reduction in the number of connections needed to secure the deck to the girder. Typically, with existing clip connectors, there is a need to use eight (8) connectors along the width of a four (4) foot deck panel. In contrast, the present invention only utilizes a maximum of three (3) connections along the same dimension. This simpler configuration advantageously reduces installation costs and also decreases the number of protrusions that are required in the wooden deck panel preservative treatment envelope. As a result, the service life of the deck is significantly increased.

[0013] Unlike the friction-based connection detail used in existing timber bridge applications, the system and method of the present invention feature an advanced connection that provides reliable, direct mechanical resistance to loading between a wood-based deck panel and a girder.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other advantages of the present invention will become more readily apparent upon reading the following detailed description and upon reference to the drawings, in which:

[0015] FIGS. 1-6 depict in cross sectional view deck designs utilizing the connection system of the present invention;

[0016]FIG. 7 depicts an isometric view of the connection system according FIG. 1;

[0017]FIG. 8 depicts a top view of a glued-laminated deck panel pursuant to the present invention;

[0018]FIG. 9 illustrates a wood deck connection device used in existing bridge construction for fastening timber decks to steel girder systems;

[0019]FIG. 10 is a graph illustrating the performance differences between the connection system according to FIG. 1 of the present invention and the connection detail depicted in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Referring now to the drawings, and more particularly to FIG. 1, there is shown some of the features which make up the deck connection system and method pursuant to this invention. The deck connection system 17 of the present embodiment comprises a principal load carrying structure, i.e. a girder 8 fabricated from a steel material, which supports a wood-based deck panel 9 containing a receiver hole. As is evident from the drawing, the receiver hole runs through the deck panel 9 beginning on an upper surface of the panel and terminating on a lower surface of the panel. A headed shear stud 10, secured at its shank to an upper portion of the girder 8, projects upwardly into the receiver hole located within the assembled deck panel 9 and is mechanically bonded to a grout agent 12 that substantially plugs the hole.

[0021] It should be appreciated that any vertical headed connector (also referred to as an “anchoring device”) having a head diameter larger than the diameter of its shank may be employed in conjunction with the present invention. Representative connectors include shear studs, bolts, lag bolts, screws, threaded connectors and deformed connectors. Two types of shear studs preferred for use with welding applications are the Nelson H4L and S3L Headed Studs™ manufactured by Nelson Stud Welding, Inc., Elyria, Ohio. These studs may be welded with an electric arc welding process through use of stud welding guns covered by U.S. Pat. Nos. 6,175,094 and 6,163,005, which are incorporated herein by reference in their entirety. The technology is generally described in U.S. Pat. Nos. 3,532,851; 3,679,860 and 4,019,013 which are incorporated herein in their entirety. A preferred method of welding includes a headed stud that serves as an electrode during the welding process.

[0022] Once the grout 12 is placed into the receiver hole, the grout 12 must sufficiently cure before the decking system can be used. Cure time will vary according to the specific type of grout agent employed and the environmental conditions in existence at the time of deck installation. Any number of currently available non-shrink grout agents may be used in the present invention. One essential benefit of non-shrink grout is that it advantageously maintains intimate contact between the wooden deck panel 9 and the grout plug 12. It is also preferable that the non-shrink grout agent possess self-leveling properties. A preferred non-shrink grout agent formulation having self-leveling properties is Sikadur 42 Grout Pak™ manufactured by Sika Corporation.

[0023] It should be emphasized that the adhesive quality of the grout 12 is not important to the capacity of the connection of the present invention. Rather, it is the positive and permanent mechanical connection between the headed connector and underlying girder, coupled with the grout and the multi-diameter geometry of the receiver hole that is critical. The mechanical properties of the grout agent 12, however, are directly related to the capacity of the connection since it is the cured grout plug 12 that provides the direct mechanical connection between the headed connector and the timber deck panel 9.

[0024] Test results pertaining to the wooden deck 9 and steel girder 8 system illustrated in FIG. 1 reveal that the mechanical connection between the headed stud 10 and steel girder 8 has a five percent offset yield strength that is 4.6 times greater than the friction-based connection detail used in conventional bridge deck units in direct withdrawal, 10.6 times greater in shear perpendicular to grain, and 11.6 times greater in shear parallel to grain. Furthermore, the connection exhibits ductile behavior when exposed to increasing loads. At no point will the connection configuration fracture or exhibit any abrupt loss of load capacity. Upon experiencing deflections in excess of a quarter inch, the connection remains completely intact. Only upon the application of excessive mechanical force and mechanical abrasion is it possible to sever the connection for direct inspection.

[0025] The vertical headed shear stud 10 can be affixed to a top surface of the steel girder 8 by means of any appropriate fastening technique, however, it is preferable to use welding technology to ensure a solid connection between the stud 10 and the steel girder 8. A weld joint 11 formed at the base of the stud shank securely anchors the headed stud 10 in place. The stud 10 is welded to the girder 8 such that the stud 10 extends upwardly through a receiver hole cut within the deck panel 9. FIG. 7 provides an isometric view of an assembled deck system 32 having several vertical studs 10 (partially shown) welded to the top surface of the steel girder 8 at longitudinally spaced intervals.

[0026] It is generally desirable to have the headed connector of the present invention secured to the supporting girder prior to placement of the wooden deck panel 9. This affords the ability to institute a greater degree of quality control on the vital connector-girder connection than is possible if the deck 9 is laid prior to the connection being made.

[0027] As is evident from FIGS. 1-7, the bottom surface of the deck panel 9 rests on the girder support. In instances where the headed connector is fastened to the girder prior to the laying of the panel 9, a receiver hole cut through the deck panel 9 is specifically arranged to line up with the connector. This is not a difficult task as the connector projects upward and is easily visible to workers. The size of the receiver hole is typically much larger than the headed connector for large construction tolerances.

[0028] Likewise, if the connector is to be fastened subsequent to installation of the deck panel 9, the receiver hole allows the connector to be placed into the hole and onto the underlying girder, and to be secured to the girder by workers on the surface of the assembled deck panel 9. The receiver hole further provides an entry point for depositing the grout agent 12 into the hole from the surface of the panel 9.

[0029] As noted above, at least one receiver hole runs through the deck panel 9. The receiver hole need not comprise a predetermined diameter. It is only important that the hole has an overall diameter that allows a worker to adequately place the deck panel 9 over the headed connector and to place the grout 12 within the hole. As is shown in FIGS. 1-6, an individual hole may comprise a plurality of diameters. On balance, the relatively large size of the inner diameter of the receiver hole affords a large construction tolerance with respect to the deck-connector alignment, thus increasing constructability and reducing construction costs.

[0030] For ease and speed of installation, it is preferable to use a prefabricated panel system and to minimize the amount of field fabrication on such system. To this end, receiver holes can be cut in the wood-based panels 9 at a deck fabrication facility rather than at the construction site. Furthermore, the forming of receiver holes in the panels 9 of the present invention at a point prior to the application of a preservative treatment process advantageously reduces the possibility that the wooden panel 9 will suffer decay.

[0031]FIGS. 1, 4, 5 and 6 depict a steel girder construction design 17, whereas FIGS. 2 and 3 illustrate timber and concrete girder construction designs 18, 19, respectively. Each of the foregoing girder systems is suitable for use with the present invention. In addition, the deck panel 9 according to the present invention may be made of a variety of wood-based materials: such as, hardwood, softwood, solid sawn timber, nail-laminated timber, glued-laminated timber, stress-laminated timber, parallel stranded lumber, laminated stranded lumber and laminated veneer lumber.

[0032] Referring again to FIG. 2, a cross sectional view of a deck connection system 18 installed according to the present invention is shown. Pursuant to this embodiment, a wooden girder 13, supports a wood-based deck panel 9 containing a receiver hole. A vertical headed lag bolt 14 screwed through an upper surface of the wooden girder 13 pierces a top portion of the girder 13. This allows for the complete securement of the headed bolt 14 to the underlying girder system 13. As previously noted, other headed connectors known in the art may be utilized. The girder 13-secured lag bolt 14 projects up through the receiver hole and bonds with a grout agent 12 filling the hole. As noted above, it is preferable that the lag bolt is 14 secured to the wooden girder 13 prior to installation of the decking 9. In any case, it should be appreciated that the entire connection system 18 can be installed from the surface of an assembled deck panel 9.

[0033] Referring now to FIG. 3, an alternative embodiment of a deck connection system 19 is disclosed that utilizes a concrete girder 15 to support the wooden decking 9. A headed deformed shear stud 16 secured to the concrete girder 15 extends upward and into a receiver hole located in the panel 9. The stud 16 is mechanically bonded to a grout agent 12 disposed within the receiver hole, and in turn, the grout is 12 bonded to the assembled wooden deck panel 9.

[0034] The headed deformed stud 16 may be secured to a concrete girder 15 of a deck unit to be constructed by placing the stud 16 into a concrete girder formwork prior to concrete placement. The stud 16 is positioned within the girder formwork in a substantially vertical direction. Upon placement of the concrete girder 15, the vertical headed stud 16 is positively secured to the concrete girder 15. Alternatively, the headed deformed shear stud 16 shown in FIG. 3 may be securely anchored to an existing concrete girder system, such as a deteriorated bridge girder undergoing restoration. This procedure comprises vertically placing a headed deformed shear stud 16 into a hole formed in an existing concrete girder 15 via drilling or other means and bonding the stud 16 thereto by means of a concrete bonding process.

[0035] Referring now to FIG. 7, an isometric view of a deck connection system 32 according to FIG. 1 is shown. As shown in FIG. 7, a wood-based deck panel 9 having receiver holes bored therein is mounted upon an upper surface of a steel girder 8 having headed shear studs 10 (partially shown) securely fastened thereto. Grout 12 disposed within the receiver holes respectively bonds to the wooden deck panel 9 and headed studs 10 positioned at longitudinally spaced intervals along the girder (partially shown). In addition to the elements and parts previously described, a pair of stiffener beams 20, 21 are shown which may be introduced during the installation process.

[0036]FIG. 8 depicts a top view of a single glued-laminated panel 22 with integrated stiffener beams 23-26 looking down on longitudinally spaced and grout filled receiver holes having headed connectors 34 embedded therein. It can be seen that the glued-laminated panel 22 rests on a supporting girder 27, and the girder 27 has headed connectors fastened thereon. Anchorage of the panel 22 is achieved by virtue of the mechanical connection between the headed connector 34 and the girder 27 coupled with the bonding activity between the grout, headed connector 34, and panel 22. This typical construction configuration 33 employs representative measurements and calculated spacing for positioning of each connector 34 along the girder system 27. Finally, like the embodiments discussed above with respect to FIGS. 1-7, the entire system can be installed from the top of the panel 22. The entire system and method of installing the system are the same as that disclosed with respect to FIGS. 1-7.

[0037]FIG. 9 depicts a cross-sectional view of a typical offset shoe connector 28 used in existing wood deck on steel girder bridge construction for fastening wooden deck panels 29 to steel girders 30. Also shown in FIG. 9 is a lag bolt 31 secured to the bottom surface of the wooden deck panel 29. Performance differences between the offset shoe connector 28 according to FIG. 9 and the wood deck to steel girder connection system as illustrated in FIG. 1 of the present invention are presented in FIG. 10.

[0038] From the drawings and the above description, it is apparent that a wood deck connection system constructed in accordance with the present invention provides desirable features and advantages. For example, the deck connection system provides for excellent corrosion resistance, enables top-side installation of deck panels, and provides improved shear strength, withdrawal resistance, reliability and fatigue behavior of the deck system. As a result, the service life of a deck is significantly increased.

[0039] The connection detail comprising the specialized receiver hole configuration, cured grout agent, and headed connector of the present invention provides a true mechanical load transfer mechanism between a wood-based deck panel and a girder.

[0040] Although many of the previous examples were directed to wood deck bridge systems, the system according to the present invention is appropriate for use with any application involving the installation of wood-based deck panels onto a girder system (e.g. floor system installation).

[0041] While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various alterations in form and detail may be made therein without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A method of creating a mechanical connection between a deck panel and a support member, comprising: (a) securing a distal end of at least one headed anchoring device to an upper portion of said support member; (b) providing a deck panel of a wood-based material, said panel having at least one receiver hole formed therein; (c) placing the wood-based deck panel onto an upper surface of said support member so that at least one headed anchoring device projects into at least one receiver hole; (d) depositing grout into at least one receiver hole to a point approximately at or above the top of the anchoring device; and (e) curing the grout to bond to at least one headed anchoring device and to said deck panel.
 2. The method of claim 1 wherein said anchoring device securing step takes place after the step of placing the deck panel onto said support member.
 3. The method of claim 1 adapted for use in a floor system.
 4. The method of claim 1 adapted for use in a bridge system.
 5. The method of claim 1 wherein the grout used is a non-shrink grout.
 6. The method of claim 1 wherein the length of the hole is non-cylindrical and contains two or more diameters.
 7. The method of claim 1 wherein said deck panel comprises a material made of hardwood, softwood, solid sawn timber, nail-laminated timber, glue-laminated timber, stress-laminated timber, parallel stranded lumber, laminated stranded lumber or laminated veneer lumber.
 8. The method of claim 1 wherein said support member comprises a material made of steel, concrete or wood.
 9. The method of claim 1 wherein the headed anchoring device is welded to a steel support member through an electric arc welding process.
 10. The method of claim 9 wherein the arc welding process uses a stud welding gun wherein said headed anchoring device serves as the electrode during the welding process.
 11. A deck connection system formed by the method of claim
 1. 12. A wood deck connection system, comprising: (a) a support member; (b) a wood-based deck panel having a top surface and a bottom surface, and having at least one receiver hole projecting from said top surface down through to said bottom surface, said panel being mounted upon said support member; (c) at least one headed anchoring device secured vertically to said support member at a position wherein at least one headed anchoring device will project into at least one receiver hole; and (d) grout deposited and cured within at least one receiver hole to a point approximately at or above the top of the headed anchoring device.
 13. The wood deck connection system of claim 12 wherein said deck panel comprises a material made of hardwood, softwood, solid sawn timber, nail-laminated timber, glue-laminated timber, stress-laminated timber, parallel stranded lumber, laminated stranded lumber or laminated veneer lumber.
 14. The wood deck connection system of claim 12 further comprising a plurality of deck connection systems located at a predetermined distance from one another.
 15. The wood deck connection system of claim 12 wherein said support member comprises a material made of steel, concrete or wood.
 16. The wood deck connection system of claim 12 wherein said non-shrink grout further comprises a self-leveling grout material.
 17. The wood deck connection system of claim 12 wherein at least one headed anchoring device comprises a shear stud, bolt, lag bolt, screw, threaded anchoring device or deformed anchoring device.
 18. The wood deck connection system of claim 12 wherein at least one headed anchoring device comprises a weldable metal and is secured to said support member by welding.
 19. The wood deck connection system of claim 12 wherein at least one headed anchoring device has a length approximately equal to or less than a distance between the top surface and the bottom surface of said deck panel and a width less than a respective width of at least one receiver hole.
 20. The wood deck connection system of claim 12 wherein the length of the non-cylindrical hole contains two or more different diameters.
 21. The wood deck connection system of claim 12 wherein the headed anchoring device is welded to said support member through an electric arc welding process.
 22. The wood deck connection system of claim 21, wherein the arc welding process uses a stud welding gun wherein the headed anchoring device serves as the electrode during the welding process. 